Method and apparatus for extinguishing fires utilizing a single aqueous solution of a salt and a foaming agent



May 21, 1968 METHOD AND APPARATUS FOR EXTINGUISHING FIRES UTILIZING A G. ROTVAND 3,384,182

SINGLE AQUEOUS SOLUTION OF A SALT AND A FOAMING AGENT Filed 001.. 24, 1966 s 11 a s 6 g 12 v//// //I ///7/7 //T United States Patent "ice 3,384,182 METHOD AND APPARATUS FOR EXTINGUISHING FIRES UTILIZING A SINGLE AQUEOUS SOLU- TION OF A SALT AND A FOAMING AGENT Georges Rotvand, Paris, France, assignor to Savas, Puteaux, France, a society Filed Oct. 24, 1966, Ser. No. 589,038 Claims priority, application France, June 28, 1966,

6 Claims. for. 169-1) This invention relates to a method of and to apparatus for extinguishing a fire.

An effective way of putting out a fire consists in projecting thereon a dry extinguishing powder and, immediately afterwards or even simultaneously, an extinguishing foam. This double projection has the advantage of combining speed of extinction through the use of a dry powder with the durable action provided by the foam, particularly in the case of incomplete extinction or when there is a tendency for reignition. To carry out this method, however, is complicated and costly as it requires substantial apparatus including two thick-walled reservoirs, with one containing the dry powder and the other the solution containing a foaming agent, the reservoirs supplying the projecting devices with powder and solution via two separate conduits, the projecting devices having moreover to be handled simultaneously. It has furthermore been found that concentrated aqueous solutions of certain salts, in particular potassium acetate, with or without the admixture of a wetting or tensio-active agent, could be used to produce finely atomized jets of comparable speed and effectiveness of extinction as the dry extinguishing powders.

An object of the present invention is to make use of this known property of certain salts in concentrated solution form while associating it with means for rendering its effects durable.

The method according to the invention is characterized in that it comprises projecting successively or simultaneously on to the fire a single liquid, consisting of an aqueous solution of an extinguishing salt with an admixture of a foaming agent and possibly of a tensioactive agent, on the one hand in the form of an atomized jet and on the other hand in the form of a jet emulsified by incorporation of air.

In this connection, it has been found that the presence of a foaming agent in .the concentrated solution of extinguishing salt in no way affects the properties of the finely atomized jet obtained with this solution, and that the presence of this salt does not prevent producing a fine stable air foam due to the presence of the foaming agent and to the incorporation of air into the liquid jet. With the method according to the invention it is thus possible to obtain with one and the same extinguishing agent an action which is just as complete as that obtained so far with two extinguishing agents (dry powder and foam) requiring two complete and separate installations.

In contradistinction, the apparatus for carrying out the method according to the invention is consider-ably simplified and is characterized in that it comprises only one reservoir which contains the sole extinguishing solution and which supplies via one and the same pipe two nozzles or two groups of nozzles adapted respectively to produce a finely atomized jet and to produce an air foam.

The accompanying drawing, partly in section, illustrates diagrammatically and by way of example one embodiment of the apparatus according to the invention.

The illustrated apparatus comprises a reservoir 1 cont-aining a concentrated aqueous solution of a salt having fire extinguishing properties. The reservoir further con- 3,384,182 Patented May 21, 1968 tains a foaming agent which may, for instance, consist of a protein based emulsifying liquid or of a known synthetic emulsifying agent, e.g., an anionic phosphated ester, or of a mixture of a tensio-active agent and of a substance such as ethylene oxide having a retarding effect on combustion. A tensio-active substance can in any case be added to the solution, in particular to help atomisation.

The reservoir 1 is connected by suitable piping, for instance by a hose diagrammatically represented at 2, to dual projecting means consisting of a tube 3 on which are mounted a spraying nozzle 4 and a nozzle 5 for producing a jet of air foam.

The nozzle 4 comprises a spraying or atomizing mouthpiece consisting of a member 6 secured to the end of nozzle 4 and provided with spray openings such as 7 and 7', and of a rotary member 8 mounted on member 6 and provided with corresponding openings, such as 9 and 9. Member 8 is retained on member 6 by a screw 10 and fiuidtightness between these two members is ensured by an O-ring 11. Two rabutments, such as 12, respectively stop member 8 in a fully open position, in which openings 7, 7' etc. and 9, 9' etc. are in register, and in fully closed position, in whcih openings 7, 7 etc. are blocked off by member 8, the output of liquid being freely regulatable between these two extreme positions.

The foam generating nozzle 5 is fitted with a mouthpiece comprising an inner cylindrical member 13 connected to the tube 3 and provided with lateral holes such as 14 and 14' which open into a cavitation chamber 15 formed in an outer cylindrical member 16 rotatably mounted on member 13 through the intermediary of a sealing ring 17, with an abutment 18 defining the optimum position of member 16. The top end of the inner cylindrical sleeve member is closed off and carries a mushroom-shaped member 19 acting as a jet-breaker whose stem 20 extends with a substantial clearance, to enable the passage of the liquid through an opening 21 defined by a flange 22 in the cylindrical member 16, the top end of the latter being further formed with a cupshaped recess 23 in which is housed the head 19 of the mushroom. Moreover, the top end of member 16 carries, at a certain distance from its free edge, an annulus 24 through which passes the jet and which is provided with inwardly projecting points or teeth, such as 25, 25' and 25", acting as jet-scrapers, whereas the gap between the edge of cylinder 16 and the annulus 24 forms an inlet for air drawn in by the jet to form the foam. With a mouthpiece thus constructed, it is possible to produce, without a mixing chamber of substantial length, a fine and stable foam able to stabilize the extinguishing action of the atomized jet which is directed on to the fire either immediately before or at the same time as the foam.

I claim:

1. A method of extinguishing a fire, which comprises projecting on to said fire one and the same liquid, consisting of an aqueous solution of an extinguishing salt with an admixture of foaming agent, in the form of an atomized jet and in the form of an air emulsified jet.

2. A method as in claim 1, which comprises directing said jets simultaneously on to said fire.

3. A method as in claim 1, which comprises directing said jets successively on to said fire.

4. A method as in claim 1, wherein said aqueous solution further includes a tensio-active agent.

5. Apparatus for extinguishing a fire, comprising one reservoir for containing a single extinguishing solution, and further comprising first nozzle means for producing an atomized jet, second nozzle means for producing an air emulsified foam, and a single pipe for feeding said single extinguishing solution from said reservoir to said first and second nozzle means.

6. Apparatus as in claim 5, wherein said second nozzle means include a mouthpiece comprising an inner tubular member connected at one end to said pipe and formed with lateral holes, an outer tubular member co-axial with and surrounding said inner tubular member, sealing means between said inner and outer tubular members upstream of said lateral holes, said inner tubular member having a mushroom-shaped jet-breaking element closing 011 the opposite end thereof and consisting of a head portion surrounded by the opposite end portion of said outer tubular member and a stem portion of reduced diameter between said head portion and said other end of said inner tubular member, said outer tubular member having an internal flange portion projecting towards and surrounding the stem portion of said mushroom-shaped element to define a constricting passage through which said stem portion extends with a substantial clearance and said inner and outer tubular members defining in the region of said lateral holes a cavitation chamber com- References Cited UNITED STATES PATENTS 3/1940 Timpson 1691 2,232,053 2/ 1941 Daimler et a1. 1691 2,745,806 5/1956 Anthony et a1. 2,767,141 10/ 1956 Ratzer et a1. 2523 6/1966 Tuve et al.

M. HENSON WOOD, JR., Primary Examiner.

V. M. WIGMAN, Assistant Examiner. 

1. A METHOD OF EXTINGUISHING A FIRE, WHICH COMPRISES PROJECTING ON TO SAID FIRE ONE AND THE SAME LIQUID, CONSISTING OF AN AQUEOUS SOLUTION OF AN EXTINGUISHING SALT WITH AN ADMIXTURE OF FOAMING AGENT, IN THE FORM OF AN ATOMIZED JET AND IN THE FORM OF AN AIR EMULSIFIED JET. 